Carburetor



Dec. 20, 1955 M. B. HEFTLER 2,727,735

CARBURETOR Filed May 24. 1952 IZ I IN VEN TOR.

United States. Pateffif'O ice.

CARBURETORI Maurice Ben Heftler, Grosse Pointe Park, Micli.

Application May 24, 1952, Serial No. 289,754

3 Claims. (Cl. 261-41) It is advisable in some applications of internal combustion engines to provide means to shut off the flow of fuel to the engine when it is coasting. When the engme is not delivering power, but running at a greater speed than it would for a given throttle position with the clutch released, the intake manifold vacuum is higher than under any condition of power delivery. Such conditions of power absorption by the engine occur when, for example, the vehicle is coasting down a grade, or When the gears are being shifted. The abnormally high intake manifold vacuum has an adverse effect on the combuston in the cylinders because of the increase in dilution of the mixture leaving the carburetor by the exhaust gases left in the cylinders at the end of each exhaust stroke. The poor combustion occurring during periods of deceleration results in the discharge of partially burnt fuel into the muifler. This partially burned fuel has a bad odor, and is in fact responsible for most of the odors given olf by gasoline engines. This partially burned fuel is still combustible, and under certain conditions it will ignite in the muffler with loud and startling explosions.

The poor combustion occurring during deceleration can be avoided by shutting oif the flow of fuel to the engine during deceleration. This can be done by the use of a coasting economzer, of which there are two types. One type opens a port in the intake manfold to the atmosphere thus greatly reducing the air flow through the carburetor and its fuel delivery. The other type stops the flow of fuel delivered by the carburetor either by closing a valve in the fuel channel or by admitting air into the fuel channel.

All types of coasting economizers may sulfer delay in shutting off the fuel when coasting starts and in promptly supplying fuel to the engine when coasting stops and normal power delivery operation must be resumed when they are used with certain types of carburetors characterized by having a long idle emulsion channel. The delay is caused by the time required to empty and to refill the idle emulsion channel each time the coasting economzer operates. This invention offers means of greatly reducing the delay by providing a well or depression in the idle emulsion channel between the fuel source and the valve in the channel to admit air thereto or to close the channel, if one is used, or between the fuel source and the priming holes if the fuel flow is arrested by opening the intake manifold to the atmosphere. Such a well will also be found useful even when no coasting economzer is used because it will facilitate starting a cold engine by providing a source of fuel quickly available to the priming holes.

In the single figure of the drawing the throttle bore 1 of a downdraft carburetor is shown nearly closed by the throttle plate 2 in the idle position. A high vacuum exists below the throttle plate and this vacuum is transmitted through the lower priming hole 3, reduced by air admitted by the upper priming hole 4, conveyed through portions .5, 6, and 7 of the idle emulsion channel, further reduced 2,727,735 Patented Dee. 20, 1955 by the' anti-siphon air bleed 8 and finally applied to the idle fuel jet 9 to draw fuel through the idle fuel channel 10 from below the liquid level LL.

Valve ll at the end of channel 12 is a coasting economizer' valve which, if used, will open and admit air to p theV juncture of channels and 6 during deceleration,

thus reducing the 'suction applied to jet 9 to a value insufficient to draw fuel therefrom. It is understood that valve 11 and channel 12 may be 'omitted entirely, or they may be replaced by a valve that closes olf the communication of channel 6 to channel 5.

Channel 13 is shown connecting the top of channel 6 with channel 7 and restricted by a small hole 14.

In the ordinary downdraft carburetor, channel 7 leads directly to channel 5, Without having yany dependent portion or trap or inverted siphon. This invention provides such an inverted sphon and it works in this way. During normal engine operation channel 7 conveys an emulsion of fuel and air to the priming holes 3 and 4, propelled in part by the sucton in the manifold and in part by gravity. When delivery of fuel through jet 9 is stopped the emulsion in channels 6 and 7 separates into air and fuel, the air rising, and the fuel dropping by gravity into the bottom of the well or trap formed by the lower ends of channels 6 and 7. The separation of the fuel from the air and the accumulation of the fuel in the well is facilitated by the cross connection 13.

Delivery of fuel through jet 9 is stopped by Stopping the engine, by opening a sufliciently large hole from the atmosphere into the intake manifold, by opening valve 11, or by closing the communication between channels 5 and 6. When a well of sufficient capacity is formed by the lower positions of channels 6 and 7 delivery of fuel emulsion by the priming holes 3 and 4 stops at the same time as delivery of fuel through jet 9, or immediately thereafter. When there is no well, as is the usual construction in which channel 7 leads directly to channel 5, the fuel that is in the channels when jet 9 stops flowing drops out through the priming holes 3 and 4 by gravity.

When delivery of fuel is resumed by jet 9, occasioned by starting the engine, by closing the atmospheric port in the intake manifold, by closing valve 11, or by reestablishing communication between channels 6 and 5, no fuel is delivered by the priming holes 3 and 4, when there is no well, until suflicient fuel has been sucked up through jet 9 and air through bleed 8 to fill channel 7. This time delay may be suificient to cause the engine to stall. It can be anticipated in part by using a higher setting for the coasting economzer control system, that is, a less sensitive setting requiring a greater degree of deceleration to cause it to act, but this is undesirable in that it reduces the benefit to be obtained by a coasting economzer.

If there is a well, formed by the low portions of channels 7 and 6, solid fuel is available to the priming holes 3 and 4 almost immediately after jet 9 starts to flow. If cross channel 13 is used, the time required to empty the well is extended so that fuel from jet 9 reaches the priming holes very soon after the well is emptied of solid fuel. Recovery of normal operation after a period of deceleration is virtually immediate and without a subsequent hesitation. Restriction 14 is small in relation to the flow capacity of channels 7 and 6 so that they will be emptied of solid fuel during normal operation, but it should be large enough to equalize the pressures in the two legs of the inverted siphon during deceleration, and large enough to pass the air out of channel 7 quickly when jet 9 starts to flow.

I claim:

l. In a carburetor with an air passage, a throttle in said air passage, a constant level fuel chamber, and a channel to convey an emulsion of fuel and air from a point above the level of fuel in the fuel chamber to the air passage at 'a point between the throttle 'and 'the engine, an inverted siphon in said channel.

2. In a carburetor with an air passage, a throttle in said air passage, 'a 'constan't'lv'el fnell chinb'ei', and 'a channel to convey 'an 'e'r'nulsion f fuel and 'air from a point above the level of fuel in 'the lfuel haniber lto 'the air passage at 'a point between the 'throttl 'and 'the engine, an inverte'd 'siphon in 'said channel 'eXt'nding to Aa point below the level of fuel in the rfuel Ic'h'ainber and below the point where said 'cha'nneir'conne'c't's with said air passage.

3. In a carburetor with an 'air passage, a 'thro'ttle in said air passage, a con'st'a'nt level f 'el chainber, and a channel to l*convey an 'emulsi'o'n of -fuel and "air frorn a point above the level of fuel in the fuel chamber to the 'ii' p''s'g t "p'i''t between 1the Vtl'l'fftle and the engine, an inverted siphon in said channel extending to a point below the level of fuel in the fuel chamber and below the point where said channel connects With said air passage, and a restricted connection across said siphon.

References Cited in the file of this patent UNITED STATES PATENTS Ericson Aug. 1, 1939 2,399,637 Jones May 7, 1946 2,568,987 Brunner Sept. 25, 1951 

